I see this differently.
Its good to inform the person on the available options out there.
The rest is up to him/her.
If he/she can't or not willing to find a means to get said bike/part, he can always flag out "I'm from the US, and getting X-part is hard" or whatever ) as with any normal conversation.
Instantly writing off options just because of location does no one an good.
It decreases demand of said product even more and discourages any potential dealer to bring them in.
It obviously 'writes off' a person's ability to get something that might ultimately suit him better and he/she may even have the ability to source it (eg. relative/friend from another country; travels to the region a lot; don't mind paying; etc )